1. Field of the Invention
The present invention relates generally to a white light source employing a III-nitride based laser diode pumping a phosphor.
2. Description of the Related Art
(Note: This application references a number of different publications as indicated throughout the specification by one or more reference numbers within brackets, e.g., [x]. A list of these different publications ordered according to these reference numbers can be found below in the section entitled “References.” Each of these publications is incorporated by reference herein.)
Prior solid-state white lighting devices typically use a light emitting diode (LED) combined with one or more phosphors to convert a portion of the LED spectrum to other wavelengths in the visible region, the combination of which appears as white light. These devices already offer many advantages over traditional incandescent and fluorescent light sources, including long lifetimes, environmentally friendly designs without the need for mercury, and enormous energy savings.
Yet, the overall efficiency of LEDs remains low. For example, LEDs suffer from efficiency loss and color instability with increased operating current. Moreover, when operating an LED, the temperature will inevitably increase, resulting in a loss in efficiency for the phosphor particles as the temperature of the device increases.
In contrast to LEDs, laser diodes (LDs) do not exhibit this efficiency loss, many exhibit increased efficiency as current increases, and maintain color stability. Thus, there is a need in the art for improved solid-state white lighting devices that rely on LDs. The present invention satisfies this need.